COPD Flashcards
What investigations would you perform if suspecting COPD? What would they show?
- Spirometry (to observe if there’s reversibility) -> obstructive or restrictive lung disease; reversibility by bronchodilator (I.e. in asthma)
- Chest x-ray -> signs of infection, pulmonary oedema, hyper-inflation, emphysema
- ECG -> ischemic heart disease, arrhythmia, R sided heart strain secondary to underlying lung pathology
What are the hallmark features of COPD?
- Shortness of breath
- Chronic cough
- Sputum production
Name causes of COPD
Host:
- genetic susceptibility (eg. α1-anti-trypsin deficiency)
- other gene polymorphisms (eg. matrix metalloproteinases, TNF – α
glutathione S transferase)
Environment:
- tobacco smoke exposure
- cannabis
- other smokes
- mineral dusts (eg coal, cadmium)
What is the pathophysiology of COPD?
- Inflammation
- Goblet cell hyperplasia -> cough + sputum
- Airway narrowing -> breathlessness + wheeze
- Alveolar destruction -> breathlessness
Fibroblast -> Fibrosis -> obstructive bronchiolitis -> COPD
CD8+ T-cells -> emphysema -> COPD
Protease -> mucus hyper-secretion -> COPD
What are the typical symptoms of COPD?
- Smoker or ex-smoker aged > 35
- exertional breathlessness
- chronic cough
- regular sputum production
- winter exacerbations
- wheeze
What are the signs of COPD?
- tar-staining of fingers
- central cyanosis (if hypoxic or polycythaemic)
- tachypnoea
- chest hyperexpansion ‘barrel-shaped’
- reduced lateral and increased vertical chest expansion Ø paradoxical lower chest motion
- reduced breath sounds
- wheeze
- palpable liver edge
What FEV1/FVC ratio is indicative of obstructive lung disease (I.e. COPD)?
FEV1/FVC < 0.7
- No correction with bronchodilators
How is COPD severity scored?
GOLD scale = Global strategy for Obstructive Lung Disease
Stage 1: FEV1 ≥ 80% predicted
Stage 2: 50-79%
Stage 3: 30-49%
Stage 4: ≤ 30%
What is seen on a chest x-ray in a patient with COPD?
Often normal x-ray
- Hyper-inflated lungs
- Flattened/low diaphragm
What is seen on a CT scan in someone with COPD?
- “holes” or bullae
- Bronchial wall thickening
What happens to the blood gases in type 1 and type 2 respiratory failure?
Type 1: pH = normal pCO2 = normal pO2 = low HCO3 = normal
Type 2: Respiratory Acidosis pH = low pCO2 = high pO2 = low HCO3 = high
What is the natural history of COPD?
- Progressive decline in lung function
- Progressive dyspnea and disability
- R ventricular failure
- Exacerbation
How does R ventricular failure (Cor Pulmonale) develop in COPD?
- Hypoxia
- Pulmonary arterial vasoconstriction
- Increased pulmonary artery pressure
- R ventricular hypertrophy
- R ventricular failure
What is the treatment for COPD?
- Lifestyle advice -> Stop smoking!
- Inhaled bronchodilators
- used for symptom relief and reduce exacerbations
- SABA (short-acting b-agonists) = salbutamol, terbutaline
- LABA (long-acting b-agonists) = salmeterol, eformoteral
- Anti-muscarinics = ipratropium, tiotropium - Inhaled corticosteroids
- Reduced exacerbation frequency (if > 2/yr)
- Slows disease progression?
- Only used for severe/frequent exacerbations (if FEV1 < 50%)
- I.e. Beclomethasone, Budesonide, Fluticasone - Oral theophylline
- Bronchodilator with narrow therapeutic window
- I.e. aminophylline - Mucolytics (i.e. carbocystine)
- Reduced mucus production - Surgical procedures
- bullectomy
- Lung volume reduction surgery
- Lung transplantation - End-of-life care
What are some complications of COPD?
- Exacerbations
- Pneumonia
- Pneumothorax
- R ventricular failure (Cor Pulmonale)
- Peripheral neuropathy
- Cachexia
How would you treat an acute exacerbation of COPD in hospital?
- Oxygen (give to maintain SpO2 between 88-92%)
- High dose SABAs usually nebulised (I.e. salbutamol)
- High dose corticosteroids (prednisolone 40mg/day for 7d)
- Antibiotics If purulent sputum or very severely ill
- Reassess after 1h: if still respiratory acidosis then consider all of the following
1. IV bronchodilator (salbutamol or theophylline)
2. Urgent intensive care opinion
3. Non-invasive ventilations
4. Intubation + assisted ventilation (I.e. CPAP)
Outline the 3 lung function tests
- Spirometry -> measures the amount of air volume that you breathe in and out
- VC = vital capacity ~ FVC (forced vital capacity
- VC = volume of air that you can exhale after a full inspiration. FVC = volume of air you can forcibly exhale after the deepest breath possible. Usually very similar.
- FEV1 = Volume of air that you can forcibly exhale in 1s - Lung Diffusion Test -> provides info about how well the oxygen that you inhale moves into your bloodstream
- Inhale CO, hold breath for a few sec, then exhale
- Inhaled [CO] compared to exhaled [CO]. Results = diffusion capacity of the lungs for CO (DLCO)
- DLCO < 55% normal value = lungs do NOT efficiently absorb O2 - Lung Plethysmography -> determines how much air is in your lungs when you exhale
- restrictive = difficulty inhaling, while obstructive = difficulty exhaling
- FRC = how much air is left in the lungs after normal exhalation
- ERV = additional air forcibly expired after normal expiration (higher than expected in obstructive and decreased in restrictive)
- TLC = total lung volume
What is the pathophysiology of asthma?
Reversible airway obstruction:
- Bronchocostriction
- Bronchial mucosal oedema
- Mucus plugging
- > Inflammatory response initiated by triggers + mast cell degranulation
Name 3 bronchodilators
- Synpathomimetic agents
- Xanthines
- Magnesium
Define COPD
Lung disease characterised by chronic obstruction of lung airflow that interferes with normal breathing and is not fully reversible.
Main features include:
- Bronchoconstriction
- Mucosal oedema
- Mucosal hypersecretion
Describe how sympathomimetic agents act on bronchial smooth muscle
B2 adrenoreceptors agonists = activation of SNS = bronchodilation
- ATP turns into cAMP by adenyl cyclise = relaxation of bronchial smooth muscle
Muscarinic ACh receptors = activation of PSNS = bronchoconstriction
Name examples of short-acting and long-acting B2 agonists
Short Acting:
- Salbutamol = ventolin, airomir, salamol easi-breath
- Terbutaline = Bricanyl
Long-acting:
- Salmeterol = serevent
- Formoterol = oxis
List 6 side effects of B2 agonists
- Tachycardia
- Arrhythmia
- Myocardial ischemia
- Tremor
- Paradoxical bronchospasm
- Hypokalemia
Describe how anticholinergic drugs work
Anticholinergic drugs inhibit bronchoconstriction by antagonising muscarinic receptors of the PNS
Name examples of short-acting and long-acting anticholinergic drugs
Short-acting:
- Ipratropium bromide = atrovent
Long-acting:
- Tiotropium = spiriva
What are 3 side effects of anticholinergic drugs? In what conditions should these drugs be used with caution?
- Dry mouth
- Nausea
- Headache
Use in caution:
- Prostatic hyperplasia + bladder outflow obstruction
- Susceptible to glaucoma
Describe how xanthines work
Xanthines are phosphodiesterase inhibitors which raise intracellular cAMP -> increased bronchodilation